This invention relates generally to pulsed gas lasers and more particularly it relates to lasers of this type which utilize flexible exit gas lines, such as polymer tubing.
In a pulsed gas discharge laser, an active gas is passed through a laser cavity and is subjected to a pulsed electric field for exciting the gas molecules. This operation gives rise to pressure and temperature waves in the laser medium.
In a laser of this type it is conventional to use a vacuum pump to draw the gaseous medium from the cavity through an exit gas line. For certain laser installations, it is important for the exit gas lines to be flexible and narrow; for example, a polymer tube is a suitable line.
The present invention arises through the observation that certain enhancements to a pulsed gas laser which utilizes one or more flexible tubes for the exit gas line, or lines, can be made to improve upon the effectiveness of the flexible tube, or tubes. Although the existence of pressure and temperature waves in the exit gas is well documented, the present invention arises through the discovery that these characteristics can have an effect on the laser performance particularly with regard to the performance of the flexible tubing. Heretofore, failures in flexible tubing were believed attributable to chemical phenomena brought on by the particular laser medium interacting with the material of the flexible polymer tubing. Various attempts at improving the performance of flexible tubing by changes in composition did not achieve any noticeable improvement. Tubing performance could be improved by using much more sturdy and substantial tubing than that which would normally be thought adequate, but that would defeat the objective of using flexible tubing.
The present invention provides an improvement which comprises the inclusion of a device in cooperative association with the laser and flexible tubing which permits the use of narrow flexible tubing at an enhanced level of performance; it has the potential for expanding the operational capabilities of the laser, permitting the use of higher pulse frequencies if so desired; it also improves the useful life of narrow flexible tubing.
Briefly the invention comprises the inclusion of a walled chamber device through which the exit gas is conducted before the gas passes into a flexible line. The device is constructed and arranged to possess a particular attenuation characteristic, or characteristics. It can serve to attenuate the peak pressures which occur in the exit gas before they reach the flexible line; it can also possess a thermal attenuation characteristic which attenuates the temperatures before the gas enters the flexible lines. The preferred embodiment of the device disclosed herein comprises a cylindrical walled chamber forming an enclosed space with an inlet tube and outlet tube providing for connection of the device in an exit gas line just before the flexible line.